1. Field of the Invention
This present invention relates to an opening and closing apparatus for a microwave oven door, and more particularly to an apparatus for delaying the opening of the door for a predetermined time to protect the user's eyes from the remaining light of the lighting lamps mounted in the microwave oven.
2. Description of the Related Art
Various devices and systems for cooking apparatus have been provided up to now. Basically, the oldest heating device was known as a specific container directly contacting a heating source, with food or the like therein to which heat was applied to cook the food or the like therein.
Thereafter, cooking apparatuses using electrical energy directly or indirectly have been developed. An example is a microwave oven using microwave energy as a heating source.
A microwave oven generates microwave energy from electricity. The microwave energy impinges into the food or the like, causing molecular motion in the interior of the food, thereby heating it. The microwave oven is widely used for thawing frozen food or heating food like milk to a desired degree because of simplicity in use.
However, the microwave oven has some disadvantages caused by its manner of heating food, and it has some limits on its own heat generating capacity as well. So, it is not always appropriate for heating food. The conventional microwave oven cannot provide a good quality of cooking with rapidity because it uses only microwave energy as a heating source, that is, a single way of heating by microwave and a certain limited output of power.
For example, when food is heated by microwave energy, it is done advantageously at once internally and externally, yet this advantage turns out to be a relative disadvantage depending on the food being heated. Food like pizza is particularly difficult to cook well with microwave energy only because of its nature. Also, heating with microwave energy may remove too much water from food.
An oven related to the microwave oven has been known to make use of a different heating source. It is now in common use.
Concretely speaking, this modified microwave oven additionally includes a heater to generate heat in its interior from another heating source apart from microwaves, by which it can appropriately heat various kinds of food.
However, it is also true that the modified microwave oven does not include various functions on the whole because said heater, even in the modified microwave oven having a heater, functions just as a simply additional heating source.
As stated above, when only microwave energy is used as a heating source, several disadvantages are exposed. These disadvantages include a single way of heating by microwave, a weakness in generating power, and too much evaporation of water from the food. Also, the provision of another heater cannot solve those problems in general even when it is mounted inside of the microwave oven, since it simply serves as an additional heat source.
Unlike conventional microwave ovens as mentioned above, another cooking apparatus simply using radiant energy as the sole heating source was disclosed in U.S. Pat. No. 5,517,005, dated May 14, 1996, for "Visible light and infra-red cooking apparatus" to Westerberg et al. This cooking apparatus is able to heat the inside and outside of food appropriately by impinging high-intensity visible and infrared light rays upon food.
The door of the conventional microwave oven contacts a pair of switches connected in parallel for disconnecting the power supply of the microwave oven when the door is opened to prevent damage from the leakage of microwave energy.
But in the microwave oven having lighting lamps, light generated out of the lighting lamps do not go off instantaneously, so light remains inside for a certain period of time. Accordingly, in the case of the microwave oven having lighting lamps, it is necessary to protect the eyes of the user from the remaining light from the lighting lamps.
As shown in FIG. 1 which illustrates a conventional door of a microwave oven, latch member 3 has latch hooks 3a, 3b located at upper and lower regions of latch member 3 inside the main body 2 of the door. Latch member 3 is elastically biased by a spring 7. The latch board 5 has lockers 5a, 5b, which receive and engage latch hooks 3a, 3b, respectively, and is mounted in front of the microwave oven.
A pair of the door switches 4a, 4b which are switched on/off according to the engagement of latch hooks 3a, 3b around the lockers 5a, 5b, respectively.
FIG. 1 indicates that the door 2 is closed as biased downward by resilient force of the spring 7. The latch board 5 is arranged at the front of the microwave oven, which is engaged with the latch hooks 3a, 3b, respectively. The door switches 4a, 4b adjacent to the lockers 5a, 5b are turned on by contacting the latch hooks 3a, 3b.
With the door 2 closed, current is applied to the magnetron (not shown) which generates microwaves in accordance with an activation state of said door switches 4a, 4b, which are turned to on by the latch hooks 3a, 3b, so that food in the oven is cooked.
From this state, when the user pulls the door handle 1, the latch hooks 3a, 3b are disengaged from the lockers 5a, 5b, and the latch hooks 3a, 3b turn off the door switches 4a, 4b. In this way, when either of the door switches 4a, 4b is off, the supply of the current to the magnetron for generating microwave energy is cut off, since the door switches 4a, 4b are electrically connected in parallel.
However, in the conventional apparatus, the door 2 can open the moment the latch hooks 3a, 3b are released. The current supplied into the microwave oven is cut off the moment the door opens, and microwaves are not generated.
But the lighting lamps inside of the oven remain illuminated for about 2 seconds even if the current is off, when the door 2 opens. As a result the user may be inconvenienced by being blinded the moment the door is opened.